The effect on the life of a gear wheel by an applied torque during a number of revolutions can be calculated by conventional means. It is also appreciated that specific parameters corresponding to operational conditions for the gear wheel with applied torque will affect its susceptibility to damage. That is, this condition has an effect on the damage caused by the applied torque during revolutional operation of the gear wheel. An example of such an operational condition is the temperature of oil used to cool the gear wheel during operation. Known models for such calculations, however, lack precision.